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SCSI question ASAP please....

Q

QwertyJuan

[H]F Junkie
Joined
Aug 17, 2000
Messages
11,285
Newb to SCSI

Have a Adaptec 2940UW and want to know what I need to buy for cables. WIll anything that says it's 68 pin work??

Also, will a Seagate Model: ST39102FC work with this card??

I need to know this stuff ASAP.

QJ
 
Just a note, that model number is for a fibre channel drive, not a SCSI drive. I've got a few drives sitting around useless and unsalable because I made that mistake. As far as cabling for that card, yeah 68-pin cables are pretty much standard
 
so how come a regular SCSI drive won't work?? It says it uses SCSI 1,2,3 and UW

QJ
 
you can get adapaters for 50 pin to 68 pin, but it can slow everything on the bus down but it will work.
 
well, then you shouldn't have a problem. Just don't use fiber channel drives on it and you're fine.
 
so what was everyone saying that it wouldn't take those Seagate drives?? I just let 10 of them go on ebay for $40, and I woulda grabbed them if it woulda worked.

Wha is fibre channel??

QJ
 
Could someone also tlel me what kinda drives my card would support?? I would like to get a couple for an old dually server I have.

QJ
 
QwertyJuan said:
Could someone also tell me what kinda drives my card would support?? I would like to get a couple for an old dually server I have.

QJ
Click to expand...

Most SCSI drives are backward compatible. The 2940 is only a 40mb card, so if you were to buy a UW(40Mb), U2W(80Mb), U160(160Mb), or U320(320Mb) drive it would work as long as you have the proper cables and/or adapters for the drive. There are really only 2 cable connection choices you need to look at. 68 Pin or 80 Pin(aka: SCA hotswap connector), skip 50 pin.(Probably really hard to find these days anyway, unless it's on a SCSI CD-ROM.) Fibre Channel uses a different interface entirely.

Seagate SCSI FAQ:
http://www.seagate.com/support/kb/disc/index_faq.html#SCSI

Edit: Important note about 80 pin, the only time you would EVER perform a hotswap with these drives is with a proper RAID card and/or backplane.
 
QwertyJuan said:
so what was everyone saying that it wouldn't take those Seagate drives?? I just let 10 of them go on ebay for $40, and I woulda grabbed them if it woulda worked.

Wha is fibre channel??

QJ
Click to expand...

Because those drives are not SCSI drives, the ST39102FC is a Fiber Channel drive. (just like an IDE drive will not work with a SCSI card, so a Fibre Channel drive will not work with a SCSI card) If you want to use Fiber Channel Drives, you need a Fiber Channel controller.

I think FC is 40 pin or something like that, and 40 pin will not connect to 68 pin or 50 pin.
http://www.seagate.com/support/disc/specs/fc/st39102fc.html

==>Lazn
 
FC is actualy a serial based buss
it useses only 2 wires for data
much like sata

there are even multiple standards for it
the current one is 200MB/s

the reason for it is it allows for long latencys between the drives and the servers, up to 300M
 
So is the Cheetah 73LP ( Link) slower than a 7200rpm IDE when using the FiberChannel controller card?
 
Tiny said:
So is the Cheetah 73LP ( Link) slower than a 7200rpm IDE when using the FiberChannel controller card?
Click to expand...

What would make you think that?
FiberChannel is fairly fast. The protocol allows for more latency (so that the devices can be further apart physically) but it doesn't create latency. That drive has a 4.9ms seek time and with FC having a 200Mb/s transfer rate (faster than U160, SATA1 or IDE) it will be quite fast.

Basically a FC card can wait around longer for a device to respond before giving up, while an IDE, SCSI or SATA device would have given up and errored out already. But if it gets an answer sooner it can respond right away.

==>Lazn
 
I don't know. :(

I found some 36gb cheateahs for 10 dollars but they have the fiber channel connector. Wouldn't those saturate the PCI thru-put?
 
Tiny said:
I don't know. :(

I found some 36gb cheateahs for 10 dollars but they have the fiber channel connector. Wouldn't those saturate the PCI thru-put?
Click to expand...

Still limted to the speed of the drive. Anything over UATA 66 is fairly meaningless as far as speed goes unless you are talking fast raid arrays.

Who cares what the interface speed it, that will almost never be the limiting factor. (almost, a good modern U320 drive on a 40Mbit/s USCSI can saturate that, but normally the drive will be slower than the interface)

So yes 200Mbit/s is faster than the 133Mbit/s of the PCI bus, but you will not be pushing 133Mbit/s anyways most of the time.

edit: http://www.tweakers.net/benchdb/testcombo/22 it looks like that drive can push 68Mbit/s max. So a 200Mbit/s vs 320Mbit/s inteface will not make a difference unless you were RAIDing 4 of them in RAID 0.

==>Lazn
 
It depends more on the generation of the drive (by that I mean the internals) more so than the connector. That perticular drive is several generations old. But, it has sustained transfers of about 60 MB/s which is comperable to todays IDE drives. It's 10k though, which gives is much better seek times, and thus makes it in fact faster.

You can certainly use that drive, but a QLogic Fibre HBA card is gonna run you $1700. FC is typically reserved for use in large arrays in an enterprise environment. I wouldn't put it in a home PC.
 
Lazn_Work said:
Still limted to the speed of the drive. Anything over UATA 66 is fairly meaningless as far as speed goes unless you are talking fast raid arrays.

Who cares what the interface speed it, that will almost never be the limiting factor. (almost, a good modern U320 drive on a 40Mbit/s USCSI can saturate that, but normally the drive will be slower than the interface)

So yes 200Mbit/s is faster than the 133Mbit/s of the PCI bus, but you will not be pushing 133Mbit/s anyways most of the time.

edit: http://www.tweakers.net/benchdb/testcombo/22 it looks like that drive can push 68Mbit/s max. So a 200Mbit/s vs 320Mbit/s inteface will not make a difference unless you were RAIDing 4 of them in RAID 0.

==>Lazn
Click to expand...

Check you speeds there bud. Last time I checked FC was 2Gbit (soon to be 4) which equates to (250 theoretical or about) 200MB/s real world not 200 Mbit. Same with PCI bus, 133 MB (mega byte not mega bit). If a PCI bus was only 133Mbit (which is under 17MB/s) a PCI SATA card wouldn't do you much good (especially with everything on the bus sharing bandwidth).
 
StorageJoe said:
It depends more on the generation of the drive (by that I mean the internals) more so than the connector. That perticular drive is several generations old. But, it has sustained transfers of about 60 MB/s which is comperable to todays IDE drives. It's 10k though, which gives is much better seek times, and thus makes it in fact faster.

You can certainly use that drive, but a QLogic Fibre HBA card is gonna run you $1700. FC is typically reserved for use in large arrays in an enterprise environment. I wouldn't put it in a home PC.
Click to expand...

That stinks.
:(
 
It is very possible to make your fibre channel stuff. You can pick up fibre channel HBA on ebay for less then $100 if you know what you are looking for. There is no need for a 2gbit one because you have only 1 gbit drives. Also make sure you don't get an optical HBA only the copper ones. Getting the device to convert optical to copper is very expensive. You will also need either a back plane or get some type of sca adaptor. These are avialable and can be linked together to get multiple drives on one loop. They typically use something that has 4 connector like DB9 or cat5 cables.

So you will need one of these

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5788341264&category=44990&rd=1

A hssdc to db9 cable will be required.

Then you need something like this as well for serial cables.

FCA-3000.jpg
 
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StorageJoe said:
Check you speeds there bud. Last time I checked FC was 2Gbit (soon to be 4) which equates to (250 theoretical or about) 200MB/s real world not 200 Mbit. Same with PCI bus, 133 MB (mega byte not mega bit). If a PCI bus was only 133Mbit (which is under 17MB/s) a PCI SATA card wouldn't do you much good (especially with everything on the bus sharing bandwidth).
Click to expand...

Sorry, you are right bytes, not bits.. just a factor of 8 is all :p

==>Lazn
 
StorageJoe said:
Check you speeds there bud. Last time I checked FC was 2Gbit (soon to be 4) which equates to (250 theoretical or about) 200MB/s real world not 200 Mbit.
Click to expand...

Well, be careful about this speed as well. Fibre Channel does currently run at 2Gbit/second, but this is actually a theoretical maximum of 200MB/s. Why is that? Well, most high speed serial buses use 8b/10b encoding. So, it takes 10 bits of serial data to send 8 bits of actual data. The reason for this is to limit run lengths of 1's or 0's in the data stream so the receiving device can recover the data clock out of the stream of data itself.

And, well, if you really want to get picky FC actually runs at 1.0625Gb/s, 2.125Gb/s, or 4.250Gb/s
 
Well, I was going to link over to the FC-AL FAQ we used to have, but it looks like that thread was gutted the last time we went down and moved to the newest vBull
Looks like this sub-forum has its work cut out for itself to reconstruct all of that
 
UICompE02 said:
Well, be careful about this speed as well. Fibre Channel does currently run at 2Gbit/second, but this is actually a theoretical maximum of 200MB/s. Why is that? Well, most high speed serial buses use 8b/10b encoding. So, it takes 10 bits of serial data to send 8 bits of actual data. The reason for this is to limit run lengths of 1's or 0's in the data stream so the receiving device can recover the data clock out of the stream of data itself.

And, well, if you really want to get picky FC actually runs at 1.0625Gb/s, 2.125Gb/s, or 4.250Gb/s
Click to expand...

I stand corrected.
 
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